Foot valves which are used at the bottom of suction pipes in installations for the pumping of water are usually of the so-called "clacker" type of non-return valves, but there are two difficulties which are encountered when the liquid to be pumped is capable of entraining particulate matter such as sand, small pebbles or small pieces of rock. A foot valve according to prior art has almost invariably been of the type having a hinged closure member which, either upon hinging from an open to closure position, bears against a generally flat surface at the bottom of the valve, or a centre stem member spring loaded which serves a similar function. Such a valve is very inexpensive, but its use has resulted in a large amount of additional work for the user, since when the pump is not operating the valve is likely to be held partly open by debris in the bottom of the suction pipe, due to its initially being entrained by flow of water through the suction pipe. Thus the water which is contained within the suction pipe is free to leak back into the bottom of a bore hole, and re-starting the pump will require re-priming of the pump and this is both time consuming and in many cases quite awkward. One object of the invention therefore is to provide a valve which can be much less likely to malfunction, thereby making it more likely that the bore casing will contain water for a period of time after the valve has been closed and the pump has ceased operating.